Developer for pressure-sensitive recording sheets, aqueous dispersion of the developer and method for preparing the developer

Abstract

A developer comprising at least one polyvalent metal salt of a nuclear substituted salicylic acid of the following general formula is provided. ##STR1## In the formula, R 1 represents an alkyl group having from 1 to 12 carbon atoms, R 2 represents a hydrogen atom or an alkyl group having from 1 to 12 carbon atoms, R 3 represents a hydrogen atom or a methyl group provided that at least one of R 1 and R 2 is a secondary butyl group, a secondary hexyl group, an isohexyl group, a secondary octyl group, an isononyl group, a secondary decyl group, a secondary dodecyl group or an isododecyl group and the total number of the carbon atoms in R 1 , R 2 and R 3 is from 9 to 18, M is a polyvalent metal atom, and m is a valence of M. An aqueous dispersion containing the developer and a method for preparing the developer are also described.

What is claimed is: 
     
       1. A developer for pressure-sensitive recording sheets which comprises at least one polyvalent metal salt of a nuclear substituted salicylic acid selected from the group consisting of 3,5-disecondary hexylsalicylic acid, 3-5-diisohexylsalicylic acid, 3-secondary decylsalicylic acid, 3-secondary decyl-5-methylsalicylic acid, 3-secondary decyl-6-methylsalicylic acid, 3-secondary dodecylsalicylic acid, 3-isododecylsalicylic acid and 3-isododecyl-5-methylsalicylic acid. 
     
     
       2. An aqueous dispersion of a developer for pressure-sensitive recording sheets which comprises at least one polyvalent metal salt of a nuclear substituted salicylic acid selected from the group consisting of 3,5-disecondary hexylsalicylic acid, 3,5-diisohexylsalicylic acid, 3-secondary decylsalicylic acid, 3-secondary decyl-5-methylsalicylic acid, 3-secondary decyl-6-methylsalicylic acid, 3-secondary dodecylsalicylic acid, 3-isododecylsalicylic acid and 3-isododecyl-5-methylsalicylic acid. 
     
     
       3. A developer according to claim 1, wherein said nuclear substituted salicylic acid is a member selected from the group consisting of 3-secondary decyl-5-methylsalicylic acid, 3-secondary decyl-6-methylsalicylic acid, 3-secondary dodecylsalicylic acid, 3-isododecylsalicylic acid and 3-isododecyl-5-methylsalicylic acid. 
     
     
       4. A developer according to claim 1, wherein said polyvalent metal salt of the nuclear substituted salicylic acid is zinc salt of the nuclear substituted salicylic acid. 
     
     
       5. A method for preparing a developer for pressure-sensitive recording sheets which comprises at least one polyvalent metal salt of a nuclear substituted salicylic acid, the method comprising subjecting to double decomposition an aqueous solution of an alkali metal salt of a nuclear substituted salicylic acid selected from the group consisting of 3,5-disecondary hexylsalicylic acid, 3,5-diisohexyl-salicylic acid, 3-secondary decylsalicylic acid, 3-secondary decyl-5-methylsalicylic acid, 3-secondary decyl-6-methylsalicylic acid, 3-secondary dodecylsalicylic acid, 3-isododecylsalicylic acid and 3-isododecyl-5-methylsalicylic acid, and an aqueous solution of a water-soluble polyvalent metal salt in the presence of an organic solvent whose solubility in water is not larger than 10 wt % and which has a boiling point of from 60° C. to 180° C., thereby obtaining a polyvalent metal salt of said nuclear substituted salicylic acid.